WO97/15522 (White et al.) discloses a movable cage assembly provided for use in conjunction with a portable personnel lift. The personnel lift has a multi-sectional telescoping mast which moves between a lower, retracted position where the cage assembly is below the top of the mast and an elevated position where the movable cage assembly is raised above the top of the mast to eliminate work envelope obstructions by the mast. A cage support beam is carried by the central mast section and the cage assembly is movable on the cage support beam between a lower position which provides ground level entry when the mast is retracted and a raised position wherein the cage is above the top of the mast. A clamshell-type cage assembly is also provided wherein the upper safety rail pivots between a raised position which facilitates easy entry into the cage wherein the user does not have to stoop or use either hand to hold the cage open. The safety rail is then pulled downwardly by the user once he has entered the cage.
U.S. Pat. No. 4,638,887 (Kishi) discloses an elevating apparatus that includes a base such as a mobile chassis, a platform, a telescopic boom assembly connecting the base and the platform together, the telescopic boom assembly being composed of a plurality of telescopically coupled booms axially aligned with each other, at least one first hydraulic cylinder disposed in the telescopic boom assembly for extending and contracting the telescopic boom assembly, a pair of second parallel hydraulic cylinders operatively coupled between the telescopic boom assembly and the base for tilting the telescopic boom assembly with respect to the base, a pair of parallel third hydraulic cylinders operatively coupled between the telescopic boom assembly and the platform for keeping the platform substantially parallel to the base, and a hydraulic control system for operating the first, second, and third hydraulic cylinders in synchronism to move the platform toward and away from the base in a substantially perpendicular relation to the base while the platform is stably maintained parallel to the base.
EP 244,060 (Ream et al.) discloses a pedestal scaffold having a base member on which is mounted a mast bearing a work platform and comprising a plurality of telescopically nested mast sections which are substantially rectangular in cross section. Means for extending the mast upwardly by relative telescopic displacement of the mast sections are provided. The scaffold is characterised in that at least some said mast sections are thin-walled tubes of sheet metal with rounded corners, each being provided with at least one stiffening rib extending longitudinally in a side wall thereof, a set of inwardly projecting corner slide blocks having respective inner surfaces complementing the shape of and adapted to slide against outer corner surfaces of an inwardly adjacent mast section and a set of outwardly projecting corner slide blocks having respective outer surfaces complementing the shape of and adapted to slide against inner corner surfaces.